Atomic Layer Deposition of Oxidizer Coatings on Aluminum, Nanoparticles to Fabricate Superthermite Explosives

摘要

Report developed under STTR contract for topic AF02T007. The primary goal of this research is to establish the technical feasibility of using atomic layer deposition to produce composite thermite particles. Secondary goals were to establish the conditions for deposition of tin oxide, coat a quantity of aluminum particles with tin oxide, characterize and test the coated particles, design a larger scale system for deposition, and evaluate the economic feasibility of the process. Chemistry to deposit tin oxide on zirconia particles by atomic layer deposition was successfully developed. This established conditions to shift the chemistry to the desired aluminum particle substrate. Composite thermite particles were synthesized through this surface growth of tin oxide and were shown to be highly reactive. However, deposition was not as efficient on the aluminum particles as the zirconia particles. The measured reactivity is less than theoretically expected, however the tested particles had an atomic ratio of oxygen to aluminum of 0.28 instead of the optimum 1.5. The reactivity falls off rapidly as this ratio deviates from optimum. The process can be economically scaled in a fluidized bed with a cost of coating the particles estimated as $9/kg with a capital investment of $500,000.